Certain alkyl n-pyridylthiopicolinamides and alkyl n-pyridylthiosonicotinamides and process



CERTAIN ALKYL N- PYRIDYLTHIOPICOLIN- AMIDES AND ALKYL N-PYRIDYLTHIO- SONICOTINAMIDES AND PROCESS Francis E. Cislak, Indianapolis, Ind., assignor to Reilly Tar & Chemical Corporation, Indianapolis, 11111., a corporation of Indiana No Drawing. Application May 29, 1958 Serial No.--738,595 e 6 Claims. 01. 260-2943 This invention relates to a new composition of matter and to the process of making it. More particularly, it relates to N-pyridylthiopicolinamides and to N-pyridylthioisonicotinamides, which compounds have the following structural formulae:

on, I

I I H R N-(? N where R and R are hydrogen or lower alkyl.

In general, the thioamides of my invention are prepared by heating, abov'e 100 C., sulfur with an amino-2- picoline or an amino-4-picoline. The equation below depicts the formation of N-2'-(6-methylpyridyl)-6-amino- 2,891,958 Patented June 23, 1959 s is recovered as a yellow colored high melting solid. For

most purposes it is sufiiciently pure as obtained above. However, if a purer material is desired, the semirpure compound may be recrystallized from pyridine-ethanol.

EXAMPLE 2 N-2'- (3'-ethyl-6'-methylpyridyl -5-ethyl -6-aminothiapicolinamide z s' CzHi CH 1% CL NH N I l N z The procedure of Example 1 above is repeated with the exception that 300 grams of 2-amino-3-ethyl-6- methylpyridine are used in place of the 200 grams of 2- thiopicolinamide by the reaction of sulfur and 2-amino-6- methylpyridine.

CH NH;

Illustrative of the manner in which my invention may be practiced are the following specific examples EXAMPLE 1 N-2-(6'.,-methylpyridyl) -6-amin0thiopicolinamide V H cunts-o @NH' N g N 2 Two hundred grams of 2-amino-6-methylpyridine and 100 grams of sulfur were mixed and placed in a flask. I may use a diluent, such for example, as 3-picoline, if I desire although in general I prefer not to use any diluent. The mixture is heated to about 140 C. and while being stirred continuously is maintainediata temperature of from about 130 C. to about 150 C. for approximately six hours. Hydrogen sulfiide is evolved during the heating period. The N-2-(6'-methy1pyridyl)-6-aminothiopicolinamide formed during the heating period may be separated from the unreacted sulfur and 2-arnino6- methylpyridine in any convenient manner.

A suitable manner of isolating the N-2'-(6-methylpyridyl)-6-aminothiopicolinamide is as follows: After the reaction period is completed, the mixture is subjected to distillation under vacuum in order to remove the unreacted 2-amino-6-methylpyridine. As good a vacuum as amino-6-methy1pyridine and the heating period is increased to about 12-16 hours and N-2-(3"-ethyl-6- methylpyridyl)-5-ethyl-6-amino-thiopicolinamide is recovered.

7 EXAMPLE 3 N -4'- (2'-methylpyridyl -4-amin0th.i0pic0l inamide ll, NH?

The procedure of Example 1 is repeated with the ex ception that 200 grams of 4-amino-2-methylpyridine are used instead of the 200 grams of 2-amino-6-rnethylpyridine and N4'-(2-methy1pyridyl) 4 aminothiopicolinamide is recovered.

EXAMPLE 4 N-3 '-(6-methylpyridyl) -5-aminothiopicolinamide UNHz H The procedure of Example 1 is repeated with the exception that 200 grams of 5-amino2-methylpyridine are used in place of the 200 grams of 2-amino'-6-methylpyridine and N-3'-( 6'-methylpyridyl) -5-aminothiopicolin-' amide is recovered.

EXAMPLE 5 N -2' (4',6'-dimethylpyridyl -4-methyl-6-aminothiopicolinamide The procedure of Example 1 is repeated with the ex-- The procedure of Example 1 is repeated with the exception that 200 grams of 2-amino-4-methylpyridine are used instead of the 200 grams of 2-amino-6-methylpyridine and the heating period is increased to about 48 hours. N-2'-(4'-rnethylpyridyl) 2 aminothioisonicotinamide is recovered.

In general, I prefer to react an individual amino picoline with sulfur. However, if I so desire, I may react a mixture of aminopicolines with sulfur.

My thioamides are useful in controlling the action of non-oxidizing inorganic acids upon metals. A solution of my thioamides in high boiling coal-tar bases is particularly useful in inhibiting the action of dilute aqueous sulfuric acid upon steel.

The behavior of my thioamides indicates that they exist in two tautomeric forms. Thus, the N-2'-(6- methylpyridyl)-6-aminothiopicolinamide, in its reactions, functions as either of the tautorneric forms shown below:

The thiol form II reacts with copper ions to form the complex compound portrayed below or the complex The thioamides of my invention may be reacted with sulfur in the same manner as were the amino-picolines to give compounds having a plurality of thio groups in the molecule. For example, N-2-(6'-methy1pyridyl)-6- aminothiopicolinamide may be heated with sulfur to give the compound having the formula,

CH3ON=C0 =omN=onNm N I N N l N s11 H SH My thioamides may also be reacted with sulfur and an aromatic amine. Thus, the reaction of N-2'-(6'- methylpyridyl) 6 aminothiopicolinamide when heated with sulfur and aniline gives a thiopicolinanilide of the formula:

I N I N SH SH' Heating my thioamides with sulfur and Z-picoline or 4-picoline also gives a compound having a plurality of thiol groups in the molecule. N-2'-(6-methylpyridyl)- 6-aminothiopi coline amide upon heating with sulfur and 2-picoline gives the compound:

N I N I N SH SH The presence of a plurality of thiol groups in the molecular structure of the above compounds makes them suit-,

able for polymerization by metal atom-donor co-ordination.

I claim as my invention:

1. Compounds of the class consisting of N-pyridylthiopicolinamides and N-pyridylthioisonicotinamides which compounds have the structural formula:

and

No references cited. 

1. COMPOUNDS OF THE CLASS CONSISTING OF N-PYRIDYLTHIOPICOLINAMIDES AND N -PYRIDYLTHIOISCONICOTINAMIDES WHICH COMPOUNDS HAVE THE STRUCTURAL FORMULA: 